[Maas-devel] RFC: "Serialising" power actions

[Raphaël Badin]

[...]
>> I think there is a middle ground here: it's true that MAAS should
>> consider it is in control of the nodes; controlling (and monitoring) the
>> power state is certainly part of it.  But as Gavin pointed out, once a
>> node is deployed, it's out of the question to consider it an *error* (as
>> in, something so bad MAAS will transition a node to an error state) if
>> the actual power state is different from the expected power state.
>
> No, I disagree.  It's an error because MAAS is in control and expects it to
> be in a particular state.

That's true for all the MAAS-controlled steps: namely commissioning, 
deploying and releasing.  Not so much for 'deployed': a node at this 
stage is potentially powering up a user-managed service.  If something 
looks wrong with this node (for instance if the power state seems wrong) 
we want to issue a warning but we don't want to take the initiative to 
mark this node as failed.

>
> You cannot have a half way house, either MAAS is managing it or it is not.
> MAAS owns the network.

We want MAAS to be the tool through which you control the power state of 
the nodes; that's why we should *flag* deployed nodes that seem to be in 
the wrong power state.  That being said, I don't think we can rule out 
the possibility that a deployed server's power state will be controlled 
externally; this is mostly a matter of blending in with existing tooling 
and practices.